meta-analysis of genetic correlation between functional longevity and linear type traits in dairy cows

The present study aimed to investigate the genetic association between functional longevity and linear-type traits in dairy cows, to estimate these parameters comprehensively. for this purpose, online databases were searched to find relevant studies. finally, 143 genetic correlation estimates between functional longevity and 21 linear type traits in dairy cows from 11 unique studies were included for analysis. genetic correlations were estimated using a random-effects model in comprehensive meta-analysis (cma) software. the results indicated that all traits in the category of conformation, including stature, strength, back top line, body depth and chest width, and rump width in the category of rump traits, have a moderate negative genetic correlation with functional longevity and increasing genetic capacity of these traits leads to a reduction in the genetic merit of cows for functional longevity. in contrast, fore udder attachment, rear udder height, udder cleft, and udder depth in the category of mammary and udder and feet and legs in the category of feet and legs have a moderate positive genetic correlation with functional longevity. therefore, genetic improvement of these traits will lead to better longevity traits. overall, the results of this study indicate that linear-type traits have low to moderate genetic correlation with functional longevity in dairy cows. genetic improvement in functional longevity can be achieved by including type traits with medium or higher correlation in the selection index. of course, to enhance the functional longevity phenotype, environmental conditions must also be considered.